A well known surgical procedure for restoring vision impaired by irreversible malfunctioning of the eye's anatomical lens involves removal of the natural lens and replacement with an artificial intraocular lens, commonly referred to as an IOL.
Early IOL's utilized lenses made of rigid material and having diameters ranging from six millimeters to eight millimeters, necessitating a commensurately large corneal incision for emplacement. More recent developments in IOL technology have made available flexible artificial lenses which are capable of being deformed by bending or curling to achieve a smaller size prior to insertion. This allows the size of the associated corneal incision to be significantly smaller, on the order of three millimeters, thus reducing trauma to the eye, post-operative astigmatism and healing time.
For some years flexible lenses were manipulated by forceps to fold or bend the lenses prior to insertion into the eye. To minimize the risk of scratching of the lenses as well as to reduce the physically exacting difficulty inherent in such manual deformation, a number of lens inserting devices have been proposed. Among these is the device disclosed in U.S. Pat. No. 4,834,094 which involves a sleeve deforming a flexible holder. Other devices are taught by U.S. Pat. No. 4,862,885, wherein the lens is collapsed between two jaws, and U.S. Pat. No. 4,934,363, which claims an external paddle that folds the lens as the paddle is retracted into a rigid tube. While each of these attempted solutions is believed by its inventor to avoid some of the problems of forcep manipulation, unsatisfactory characteristics are clearly present. For example, one such apparatus employs an elaborate and expensive drive mechanism, another involves complex ratchet and pawl operation, and a third requires a membrane along with the lens to be inserted through a cannula into the eye and then the membrane to be withdrawn from the eye.
Modern lenses may be of a three-piece configuration, having a flexible light-focussing central portion called the lens optic, and two extending arm-like members known as haptics, which hold the optic in place after the lens is inserted into the eye.
However, many intraocular lenses still in use today are of one-piece construction, having an integral radial flange fixed to the lens optic, which flange performs the haptic function of centering the optic in place within the eye.
Some previous insertion devices have been designed to manipulate the one-piece configuration of intraocular lens; an apparatus that operates well with both configurations, preparing one-piece and three-piece lenses for insertion with negligible distortion to the lens optic, would be most desirable.
In addition to the risks that may be engendered by prior insertion methods (e.g., scratching of the optic portion of the lens), there is danger of damaging the delicate haptic or fixation members. If a haptic is torn or pinched during lens insertion, the incision may have to be enlarged to permit removal of the damaged lens, thus surrendering the advantages of the smaller incision.
Surgeons who have used existing lens insertion devices have expressed that a highly satisfactory instrument would provide (1) reliable and safe release of the IOL into the eye, (2) minimal wound enlargement, (3) freedom from damage to lens optic and haptic, and (4) ease of loading the IOL into the instrument.
Accordingly, it is an object of this invention to provide a simple and inexpensive method of curling a flexible intraocular lens prior to insertion into an eye so that manual handling of the lens is minimized, reducing the danger of haptic tearing and of lens optic scratching.
Another object is to provide an instrument that will safely accommodate and implant flexible lenses with or without haptic members, i. e., of both one-piece and three-piece construction.
A further object is to provide an easy to load and operate instrument that implants a lens without requiring the insertion into the eye and withdrawal of any membrane-like part of the instrument.